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Power supply issues! PPBA


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I just sent a support request to pegasus with the following. Thought, I'll post on the forum as well, if anyone of the brilliant members here could know what the issue is? 

I recently bought a PPBA, and the pegasus PSU. Peripherals connected to the PPBA are
1. EQ6R-Pro
2. QHY8L camera 
3. RPI 4
4. ZWO EAF
5. ZWO 120mm-s camera 

Now, the issue im facing is, despite using the pegasus PSU, the voltage displayed on the PPBA control panel is 12.0V, and soon as the system is put under any load, that is camera cooling turned on, and mount slewing at full speed, the voltage drops and the PPBA cuts off all supply. I've seen the voltage drop to as low as 11.3V at times before power being cut off to all the peripherals. Once PPBA cuts off all supply, the voltage displayed in the control panel jumps back to 12.0V sometimes 12.1V.
I'm not sure why such a significant voltage drop is occurring, and if there is a problem with either the PPBA or the PSU? 
Furthermore, the temp/humidity sensor always shows humidity at 99%, and dew point 0.2 degree below the current temp, not sure if the sensor is faulty. 

 

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I cannot comment on the Pegasus PSU but I use this and have had no issues whatsoever:

https://www.firstlightoptics.com/power-accessories/nevada-psw-30-25-30a-switch-mode-power-supply.html

I send the PPBA 13.8V and never see it drop below 13.5v.

On mine I have connected to 12v:

AZ-EQ6

294MC Pro

ZWO EAF

On the adjustable 12v I have :

Mele Quieter 2 mini-pc

Dew Heaters:

2 x W&W devices

USB:

Mele PC

AZ-EQ6

294MC with 120mm and filter wheel connected to the hub

ZWO EAF

Edited by scotty38
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If the voltage is dropping like that, and assuming the Pegasus supply is regulating OK, then there must be significant resistance in the cables and/or connectors from the supply to the PPBA.

Looking at a photo of the Pegasus PSU, the cable doesn't look man enough for 10A and the connector type used is typically only rated for 5 or 6A.

I remember seeing this issue before. They have set the shut down voltage so close to the supply voltage that trouble is bound to happen. As Scotty has done - a 13.5V supply will solve it.

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1 hour ago, scotty38 said:

I cannot comment on the Pegasus PSU but I use this and have had no issues whatsoever:

https://www.firstlightoptics.com/power-accessories/nevada-psw-30-25-30a-switch-mode-power-supply.html

I send the PPBA 13.8V and never see it drop below 13.5v.

On mine I have connected to 12v:

AZ-EQ6

294MC Pro

ZWO EAF

On the adjustable 12v I have :

Mele Quieter 2 mini-pc

Dew Heaters:

2 x W&W devices

USB:

Mele PC

AZ-EQ6

294MC with 120mm and filter wheel connected to the hub

ZWO EAF

I had looked at the Nevada power supply, considering the pegasus PSU is £60, the Nevada is not far off. 

My reasons or concerns were, that I leave everything outside on the mount, under a telegizmos cover. And leaving Nevada in an weatherproof box didn't seem to sit right with me, given the heat generated. 

I did think, of running the Nevada inside, and running a long cable to the PPBA, but then voltage drops becomes a concerns again. 

How are you using the Nevada unit? Do you have a permanent obsy? 

Edited by Realtimedoctor
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I had an issue with the SestoSenso 2 reporting under voltage when I had everything powered via the PPBA. Since then I have done two things and have not experienced the problem again:

1. I moved the mount power from the PPBA to a direct 12V from the PSU.

2. I changed from this PSU to this PSU

Now it might have been either/or both these were required to resolve the issue, but since doing that I have not had any issues. 

Just add that I still use the old Nevada PSU inside at room temperature for testing equipment set ups, and don't have issues. When I did have issues it was very cold, which can have an effect.

Edited by gilesco
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It is good that the kit is running again.

Reporting the original PSU dropping to 11.3V indicates the current drawn was too high, causing the voltage to collapse.
When something (camera, raspi, anything) detects undervoltage and shuts down, current usually reduces and supply voltage recovers.

In the absence of point of load voltage vs PSU measurement, or current from PSU measured, it is not certain what caused the problem.
In other words a multimeter to provide an independent check of what is happening would clarify the situation.
An adjustable PSU allows you to reduce voltage (in daylight and warmth) to see what stops working first.
It is much better to measure and establish limits, than to lose nights of viewing.

On the Nevada PSU that doesn't like the cold. In general a PSU will be fine at slightly sub zero temperature. It is usually at high temperatures where they play up.
As soon as you start up a chilled PSU, internal self heating tends to keep it happy.
But any half decent equipment manufacturer will specify a temperature range for his product.
A brief search of Nevada products found plenty of them on sale. But nothing stating temperature & humidity limits. I couldn't find safety & EMC approvals either!
Maybe there is something in the user manuals? But I didn't find anything online.

For comparison, I pulled online data for a TDK PSU, 12V 5A. Extracts from performance stated.....

Operating Temperature - 0°C to 60°C derate linearly to 50% load from 41°C to 60°C
Storage Temperature °C -10°C to 70°C
Humidity (non condensing) %RH 10 - 90% RH

Safety Agency Certifications - UL/EN/IEC60601-1, CSA-C22.2 No.60601 3rd edition (2 x MOPP)
EMC - EN55011B, EN60601-1-2

That is typical of a consumer product. An industrial product would be much better.
 

HTH,

David.

 

 

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I have repeatedly drawn upwards of 70W through the PPBA without any problems and with the voltage well above 12.0V.  I have used a number of different power sources, 9A Pyramid, Jackery Explorer 1000, Bluetti AC50S to supply the power but never the Pegasus AC power adapter.  I wouldn't estimate your power draw to be any more than that, and much less if your camera is uncooled.  So there are 2 remaining options, either there is something wrong with your PSU or the PPBA itself.  Frankly, I haven't found the support at Pegasus to be very good for a different and subtle problem I encountered.  Let us know how this turns out.

Regards,

Curtis

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The Nevada PS-08 only manages 6-8 Amps via the cig lighter, and is 8 Amps on the tongue sittings. Also when you check the cig lighter fuse you often find that they're fitted with 5A fuses.

This was the reason I moved to the higher capacity Nevada.

I also tend to have the Nevada indoors, with a 5m Lynx Astro cable to the kit.

Anyway, I have not had issues running the kit in the way I do now. Agree that the Pegasus PSU doesn't look ideal for 10A operation (I have never used it).

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28 minutes ago, Realtimedoctor said:

I had looked at the Nevada power supply, considering the pegasus PSU is £60, the Nevada is not far off. 

My reasons or concerns were, that I leave everything outside on the mount, under a telegizmos cover. And leaving Nevada in an weatherproof box didn't seem to sit right with me, given the heat generated. 

I did think, of running the Nevada inside, and running a long cable to the PPBA, but then voltage drops becomes a concerns again. 

How are you using the Nevada unit? Do you have a permanent obsy? 

No Observatory, at least not yet it's on this years "plan". I have the PSU in one of those plastic storage boxes and it's fine for the few days at a time that I leave stuff outside. I do have a 5m silicon cable so I could have the PSU inside if needed but I've not done that to this point.

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I can't comment either on the Pegasus PSU but use the Nevada Radio 30A PSU and it's rock solid. It provides 10A through the cigarette socket output, but my rig rarely draws above 2-3A total, including mount, mini PC, dew shields, cameras/cooler, focuser and filter wheel. Only time I have an issue is if I accidentally flick the switch from 13.8V to Adjustable on the back panel - unfortunately quite easy to do when setting up.

I did use an unbranded 12V 10A power block previously and had all sorts of strange behaviour as different devices complained about under volts - the mount in particular would drop its connection. Strange that it didn't just stop slewing. From measurements, it looked like once voltage dropped to <11.5V, trouble started.

I have an almost identical set of connections to @scotty38 including the MeLE mini PC on the variable voltage output. @Realtimedoctor what ports are you using - especially for the Pi 4 which needs some juice.

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Similar experiences to @Padraic M too. I had an Amazon 10A supply that ran all my kit previously (minus the mini pc) and I thought it all worked fine. I used to see odd guiding issues that I couldn't fathom out so convinced myself it was power related and bought the Nevada. I do not have any of those issues now. I still cannot image for toffee but my guiding is always 0.6"-0.8" now with occasional forays into 0.4". I was lucky to get beneath 1.0" with the old supply. I cannot say the PSU was solely responsible but I made no other changes (the mini pc came afterwards) so make of that what you will.

I had planned to either

1. Run everything except the mount from the 13.8v output and the mount from the 12v Cigarette output or

2. Run 2 x 5m silicon cables from the 13.8v output, one to the PPBA and then one direct to the mount.

I went with option 2 and all was fine but when I saw the low current draw I made up a cable and ran the mount from the PPBA too. No discernible difference. It just works great now..... Famous last words of course in this hobby....

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I assume the PS is the 10A version ?

I did have a PPBA that ran without issues at all but like most replies here I did not run the mount via it. The main reason  why was it was easier to wire that way. With the PPBA mounted on the scope I could use relatively short usb and power cables keeping eveything neat but if I needed to run a cable to the mount (I-Optron CEM60 I needed a loo[p of cable as the PPBA moved with the scope and the mount supply port was static and this is what I was trying to avoid with the PPBA so the mount had its own cable back to its own supply.

If the PS is the 10A version then it should cope with your load so not too sure why you have this issues, all I can think of is that  although the mount is rated at 11-16V 4A then it may only take 4A (I suspect less even when fast slewing, best guess is between 2 and 3A but could be wrong) the initial accelleration of the steppers could for a short while take quite an amperage until they are moving properly. So maybe this initial drop in essense is very short but just looks more obvious because the update of the readout is fairlyslow and that initial drop is enough to make the PPBA cut out with low voltage.

Just my initial thoughts, can you try powering your mount speperately ? or is there a particular reason why you want to power the mount via the PPBA ?

Steve

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I run my mounts with power through the PPBA.  Since they are SB mounts, MyT and MX, they require 48V so I run the output from the PPBA through a DC-DC voltage converter.  This has been working for me for nearly 2 years.  I don't see why running the mount through the PPBA would be an issue anyway.  Mounts consume ~0.5A when tracking and only upwards of 1A to 1.5A when doing a high speed slew.  So not much draw for 99% of the time and not even a lot during the fast slews.  Folks greatly overestimate the power draw on a mount.  I have measured this on many mounts and the highest draws have been for my larger mount, the MX, as would be expected.  Even then it is not much.

Regards,

Curtis

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13 minutes ago, curtisca17 said:

~0.5A when tracking and only upwards of 1A to 1.5A

So 1A to 1.5A, but the initial pulse to get the mount moving can be much higher than that. All these values are time-series averaged, and so while over a 0.1 second period the max is 1.5A (to push the needle upto 1.5A), for 0.05 seconds the pulse might have been 5A, then a half-life descent to 1.5A.

A lesson I have learnt, is that ensuring your power is good is paramount to smooth running, and if you add extra electric kit in the future you are future-proofing your set up. A good PSU with plenty of power capacity is a good way of avoiding future issues as you develop the kit you use, and not all that expensive to stay on the right side of  the curve.

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I think we can say with some certainty that the PPBA itself is fine and will have no problem managing the power required to run all kit, as long as the upstream PSU can support the load. The reason I like powering everything through the PPBA is that I'm moving towards remote operation (even if remote just means in the back garden) and can integrate power-up and power-down into the NINA sequencer, using the PPBA power switches. It's a neat solution, and gives me great satisfaction!

The 30A PSU sounds like overkill, but it provides plenty of headroom and has taken away a whole load of hard-to-debug issues.

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3 hours ago, Padraic M said:

I can't comment either on the Pegasus PSU but use the Nevada Radio 30A PSU and it's rock solid. It provides 10A through the cigarette socket output, but my rig rarely draws above 2-3A total, including mount, mini PC, dew shields, cameras/cooler, focuser and filter wheel. Only time I have an issue is if I accidentally flick the switch from 13.8V to Adjustable on the back panel - unfortunately quite easy to do when setting up.

I did use an unbranded 12V 10A power block previously and had all sorts of strange behaviour as different devices complained about under volts - the mount in particular would drop its connection. Strange that it didn't just stop slewing. From measurements, it looked like once voltage dropped to <11.5V, trouble started.

I have an almost identical set of connections to @scotty38 including the MeLE mini PC on the variable voltage output. @Realtimedoctor what ports are you using - especially for the Pi 4 which needs some juice.

Hi, 

The pi4 is connected to the USB - 1 port on the PPBA. It powers well, even when PPBA cuts off power to everything else, due to voltage drop, the USB reports remain powered. So the RPI continues to run, without any issues. 

It's the reason, why I'm able to see the voltage drops in the PPBA indi control panel. 

 

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2 hours ago, teoria_del_big_bang said:

I assume the PS is the 10A version ?

I did have a PPBA that ran without issues at all but like most replies here I did not run the mount via it. The main reason  why was it was easier to wire that way. With the PPBA mounted on the scope I could use relatively short usb and power cables keeping eveything neat but if I needed to run a cable to the mount (I-Optron CEM60 I needed a loo[p of cable as the PPBA moved with the scope and the mount supply port was static and this is what I was trying to avoid with the PPBA so the mount had its own cable back to its own supply.

If the PS is the 10A version then it should cope with your load so not too sure why you have this issues, all I can think of is that  although the mount is rated at 11-16V 4A then it may only take 4A (I suspect less even when fast slewing, best guess is between 2 and 3A but could be wrong) the initial accelleration of the steppers could for a short while take quite an amperage until they are moving properly. So maybe this initial drop in essense is very short but just looks more obvious because the update of the readout is fairlyslow and that initial drop is enough to make the PPBA cut out with low voltage.

Just my initial thoughts, can you try powering your mount speperately ? or is there a particular reason why you want to power the mount via the PPBA ?

Steve

Hi Steve, 

 

Yes this is the 10A version PSU that pegasus sell. 

The reason, I'm powering everything with the PPBA, is that keeps my set up quite clean. I only have one wire that goes up my scope to power the PPBA. Everything else is attached to the PPBA, and stays mounted on the dovetail. 

Powering the mount with another PSU is certainly doable, but as some have noted, that PPBA should be able to power everything I've connected to it at the moment. 

I'm going to get a temp big ac/dc converter to power the PPBA, and see if the voltage drops. If it does, then there is certainly something wrong with the PPBA, if it doesn't then its the PSU. 

I can't think of any other reason the voltage will drop. Something has to give, and I think it's the PSU that isn't doing its job correctly. 

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You may have a fault on one of the devices connected. The fault could be dragging the voltage down and the ppba is then shutting the lot off. Try different combinations of your stuff leaving one device off at a time to see if that can identify anything.

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3 hours ago, gilesco said:

So 1A to 1.5A, but the initial pulse to get the mount moving can be much higher than that. All these values are time-series averaged, and so while over a 0.1 second period the max is 1.5A (to push the needle upto 1.5A), for 0.05 seconds the pulse might have been 5A, then a half-life descent to 1.5A.

A lesson I have learnt, is that ensuring your power is good is paramount to smooth running, and if you add extra electric kit in the future you are future-proofing your set up. A good PSU with plenty of power capacity is a good way of avoiding future issues as you develop the kit you use, and not all that expensive to stay on the right side of  the curve.

I don't for a minute believe any of the typical mounts draw anything close to 5A even as a transient.  The 1.5A is the transient value.  And that is with a very large mount with a C11 and a bunch of accessories.

Really, mounts draw very little.  After all loads are balanced.  But I won't press the point any further.

Regards,

Curtis

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  • 4 months later...
40 minutes ago, 04Stefan07 said:

Looks very similar in spec to the Nevada PSW-30 - practically identical, although the Nevada can apparently deliver 25A continuous, while this one states 20A continuous.

They are both built for the same application - CB / Ham Radio Enthusiasts.

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